U.S. Pat. Nos. 4,941,936 and 4,941,937 both issued Jul. 17, 1990 teach a method of heating an adhesive between two fiber reinforced plastic members using a high frequency electric field. The electric field causes the dielectric heating of the adhesive between the fiber reinforced plastic members. The members are placed between two electrodes and an electric field is passed linearly from the top electrode through the members to the bottom electrode.
The present invention is specifically intended for the manufacture of automotive headlamp assemblies. Current automotive headlamps are manufactured by bonding a metallized reflector to a transparent lens. Both the reflector and the lens are generally made of a thermoplastic material such as polycarbonate. A two component epoxy adhesive is placed between the lens and reflector and allowed to cure. After the lamp assembly has cured, it is pressurized to approximately 5 p.s.i. to detect any adhesive failures or leakage. Pressure testing of the lamp assembly requires sufficient cure of the adhesive to withstand the increased pressure.
It is an object of the present invention to provide a rapid method of curing an adhesive between two thermoplastic members. It is another object of the present invention to provide a method for dielectrically heating an adhesive using a fringe electric field. It is a further object of the present invention to provide a method for dielectrically heating an adhesive between an automotive reflector and lens assembly.